Synchronizing signal generation system



9 K. SCHLESINGER 2,227,012

SYNCHRONIZING SIGNAL GENERATION SYSTEM Filed Nov. 10. 1956 m'a'm'Patented Dec. 31, 1940 PATENT OFFICE 2,227,012 sYNonnoNIzmGSIGNALIQGENERATION l l l sYsTE Kurt Schlesinger, Berlin, Germany,assignor, by mesne assignments, to Loewe Radio, Inc-, a corpora tion ofNew York Application November 10, 1936, SerialNoi 110,042 r InGermanyNovember 18, 1935 team's; (01. 178-72) In the case of televisionscanning devices, which operate by the scanning of a multi-cellphoto-electric screen by means of a cathode ray, there has been employedheretofore, according to publications which have become known, a

mechanical device, usually a light siren, for producing the correctdeflection frequencies, and synchronization signals have been producedby the same means. A method of this kind does not produce thesynchronous signals as a matter of course only when the scanning my hasreached the edge of the photo-electric screen, but the initiation of thesynchronization signal depends on the particular oscillation conditionsof the siren,

which is coupled more or less loosely with the movement of the ray. Itis known that in the case of electrically generated synchronizationsignals of this nature curvatures of the image co-ordinates veryfrequently occur. Even a humming component in the mains-connectedapparatus may give rise to deviations from the straight line as regardsthe edges of the image.

Curvatures of this kind in the co-ordinates may be fundamentallyobviated in an arrange- 5 ment operating with scanning disc when thescanning image point itself causes the synchronization signal, viz.,when it reaches a prescribed edge of the image. It is then immaterialwhether the scanning point arrives at the edge of the 39 image withsmall errors in time-too early or too late. The synchronization signalis always initiated in such fashion that the reversing points of thesynchronized received-image point are all situated on a completelystraight marginal line,

35 which in these cases is the transmitted television image of thestraight edge of the transmission screen. Errors in the movement of theimage point are accordingly eliminated automatically in the method ofthe self-synchronizing scan- 40 ning point. This method may be referredto generally as auto-synchronization.

The present invention sets forth auto-synchronization methods in thecase of the ikonoscope.

45 The invention relates to a transmission whereby the synchronizingsignals have an amplitude different from that of the image contentssignals. There is assumed to exist in an ikonoscope system anintercepting plate I, which in 50 the known fashion is made up of a cellmosaic. The plate is scanned in lines by a cathode ray 2, which proceedsfrom an electron-optical system 3/4 and projects on to the plate asufficiently sharp scanning point.

The method which solves the problem of synchronization of theikonoscopewithout mechanically moved devices is illustrated in the drawing. Thisconsists in the use of an amplitude filtering method as applied to thedeflecting potentials. There are shown behind the anode 3 5 of theray-generating system the first deflecting plates Ill. They areconnected with a relaxation generator II, which is preferably applied tothe plates in push-pull. An amplitude filter consisting of a simpletwo-electrode valve I2 is con- 1 nected by its anode to that particularplate H) which upon the deflection of the ray conducts positivepotentials to the synchronizing edge. The potential of a,biasing battery[3 is selected to be somewhat lower than the maximum 15 potential valueat the deflecting plate In. In consequence, after the potential value 13has been exceeded, the amplitude filter I2 is traversed by an impulsewhich, in the manner known per se, may be tapped by the transformer I4and ad- 20 ditionally utilized.

Since the deflecting potential is closely associated with thegeometrical position of the scanning ray 2 on the mosaic plate I, theremay be obtained also in this purely electrical fashion the occurrence ofsynchronization impulses corresponding with a straight edge of the imageand adjusting the same at the receiver, even if the deflecting generatorH is affected by interfering modulations.

The inclusion of a potentiometer between the relaxation generator andthe amplitude filter, which may be purely galvanic or may also contain acondenser, may naturally be made use of with the advantage that thecounter-battery I3 requires to have a lower voltage. A lower limit inrespect of the distribution of the potential is provided by theinsecurity limit of the amplitude filter l2 (starting current range=afew volts).

According to the invention, the synchronization impulses from thetransformer l4 may be utilized for suppressing the aerial current or, asshown in the drawing, they may also be added in direct fashion in thecorrect polarity to the main amplifier connected with the signal plate5, which represents a simplification in the electrical apparatus by theomission of special synchroniza- 'tion amplifiers. The transformer I4 ispreferably tuned to the duration of the impulses, and if necessary, forthe purpose of eliminating the oscillatory counter-impulse of theinduction, must act on the amplifier B by way of a rectifier l 5,.

In all of these synchronization methods, which make use of the cathoderay itself or its deflecting potentials for obtaining thesynchronization signals, the possibility is provided of employing ascontrol frequency for the line frequency one of the known stationaryfrequency standards, for

example quartz, magnetcstrictive rods and the like. The receiver followsin positive fashion the given number of lines of the transmitter, andthe use of rotating sirens may be dispensed with.

I claim: 1. In a television transmitting system, a cathode ray tube,means for developing a cathode ray wave form onto said unidirectionalconducting means, means for maintaining said .first unidirectionalconducting means at a predetermined threshold response state, a firstinductive means connected with said first unidirectional conductingmeans and having at least a portion of the current passing through saidfirst unidirectionas conducting means impressed thereon, a secondinductive means coupled with said first inductive means, a secondunidirectional conductor electrically connected to said second inductivemeans for rectifying the current passing through said secondunidirectional conductor, and means for mixing the signals passingthrough said second inductive means and said second rectifier with thesignals occurring in the target output circuit.

2. A system as claimed in claim 1 wherein said means to deflect thecathode ray beam comprises a pair of electrostatic plates and whereinthe energy supplied to the first unidirectional conductor comprises aportion of the energy impressed upon one of said electrostatic plates.

.' I v t t KURT SCHLESINGER.

